Connecting element for a winding of an electric machine

ABSTRACT

An interconnection element for a multi-phase winding ( 11 ) that is comprised of coils ( 12 ) and belongs to an electric machine, in particular a brushless mini motor, having a support ( 20 ) made of insulating material and conducting strips that are disposed on the support ( 20 ) for producing interconnections among the coils ( 12 ). In order to reduce materials costs, the conducting strips are embodied in the form of bent wires ( 27 - 30 ) that are preferably contained in channels embodied in the support ( 20 ) and are fixed in place by means of two annular cover elements ( 31, 32 ) made of insulating material (FIG.  1 ).

PRIOR ART

The invention is based on an interconnection element for a multiphasewinding that is comprised of coils and is part of an electrical machine,in particular a brushless mini motor, as generically defined by thepreamble to claim 1.

In a known interconnection element of this type (EP 1 062 720 B1), thesupport made of insulating material is embodied in the form of asupporting plate, which, together with a stator body that is embodied inthe form of a lamination bundle and supports the winding, is fastened bymeans of a hub to a bearing support tube that is in turn attached to amotor flange. The electrical conducting strips for producinginterconnections among the coils are embodied as conductor rails thatare manufactured as stamped parts and are fastened to the supportingplate, concentric to the hub. A first conductor rail, which has tabsextending at angles in relation to the conductor rail to form a starpoint, is connected to the coil ends of all of the winding phases. Threeother conductor rails are attached to the supporting plate, arrangedconcentrically around the first conductor rail, their tabs arrayed forconnection to the coil beginnings. In order to avoid crossing pointsbetween the concentric rails and the tabs protruding from them, the tabsof the second conductor rail are routed under the third conductor railand the fourth conductor rail by means of sunken guides in thesupporting plate and the tabs of the third conductor rail are alsorouted under the fourth conductor rail by means of sunken guides. Whenmanufacturing the conductor rails that are comprised of stampedmaterial, in order to keep waste within limits, the first and thirdconductor rails are manufactured in a first stamping die and the secondand fourth conductor rails are manufactured in a second stamping die,each in its own stamping procedure, the second, third, and fourthconductor rails each being provided with a connecting tab forlitz-connections.

ADVANTAGES OF THE INVENTION

The interconnection element according to the present invention, with thecharacteristics of claim 1 has the advantage that using bent wires forthe electric conducting strips achieves a drastic reduction in themetal-related material costs for the interconnection element since inparticular, this eliminates the enormous material waste generated bystamping, which can be up to 80% with the known interconnection element.The material waste is limited solely to the trimming of the wire endspossibly required by the manufacturing process. The substantialelimination of material waste also advantageously reduces disposalcosts. Using simple wire-bending—the wires can have a round or polygonalcross section (rectangular, square, hexagonal, etc.)—makes it possibleto replace stamping dies with inexpensive bending and handling tools.Plants that do not require a separate stamping station can manufacturethe interconnection element according to the present invention by usingthe simple, inexpensive wire bending process, which can be implementedfor only minimal investment costs, thus permitting companies to increasetheir real net output.

Advantageous modifications and improvements of the interconnectionelement disclosed in claim 1 are possible by means of the steps taken inthe remaining claims 2 through 9.

According to an advantageous embodiment form of the present invention,the support is embodied in the form of a circular plastic ring withcoaxial channels provided to accommodate the wires, which channels arepartly open at the sides and are offset from one another, partly in theradial direction and partly in the axial direction. The circular plasticring, whose radial width approximately corresponds to the radialthickness of the yoke ring of the stator of the motor, is manufacturedas an injection-molded part whose slender annular form further reducesmaterials costs in comparison to the supporting plate with the knowninterconnection element.

Claims 10 through 13 disclose a stator in which the interconnectionelement according to the present invention is used.

DRAWINGS

The invention will be explained in greater detail in the descriptionbelow in conjunction with an exemplary embodiment shown in the drawings.

FIG. 1 shows a perspective top view of an interconnection element for awinding in the stator of a brushless mini motor, in association with thestator,

FIG. 2 is a perspective, exploded view of the interconnection elementaccording to FIG. 1,

FIG. 3 is a perspective, exploded bottom view of the interconnectionelement in FIG. 1.

DESCRIPTION OF THE EXEMPLARY EMBODIMENT

The interconnection element 10 shown in the perspective top view in FIG.1 is conceived for a three-phase winding 11 with a total of nine coils12 of a stator 13 of a brushless mini motor, which can be anelectronically commutated direct current motor (EC motor) or asynchronous motor. The stator 13 depicted in a perspective view in FIG.1 has a stator body 14, which, in an intrinsically known way, includes ahollow cylindrical yoke ring 15 and, in the exemplary embodiment, atotal of nine stator teeth 16 protruding radially from it, which, with arotor that is not shown here, delimit the working air gap of the motor.An annular coil 12 is wound onto each stator tooth 16 and the coil ends121 and 122 of each coil 12 are attached to a respective flat connectingpin 17. The connecting pins 17 are disposed equidistantly in thecircumference direction and protrude axially from the end surface of theyoke ring 15; they are electrically insulated from the yoke ring 15 byan insulation ring 18.

The interconnection element 10 is used to produce interconnections amongthe coils 12; in the example described, the interconnections are laidout so that each phase belt or winding phase of the three-phase winding11 has three coils 12 connected in parallel.

The interconnection element 10, an exploded view of which is shown fromabove in FIG. 2 and from below in FIG. 3, has an annular support 20 madeof plastic that has a total of four coaxial channels 23-26, each foraccommodating one of a total of four bent wires 27 through 30 that serveto interconnect the coils 12. Two channels 24 and 26 are radially offsetin a plane of the support 20, i.e. are concentric to each other. Theupper channel 23 and the lower channel 26 are axially offset in relationto the channels 24, 25 in the shared middle plane of the support 20 andhave channel openings 231 and 261 in their outer annular wall. The upperchannel 23 is also offset radially inward in relation to the channels 24and 25. The corresponding bent wires 27 through 30 are accommodated inthe channels 23 through 26 and are fixed therein by means of two annularcover elements 31, 32 made of plastic that are placed axially againstthe support 20 from above and below. The upper cover element 31 closesthe upper channel 25 and, with axially downward-protruding closingbodies 33 that project radially beyond the cover element 31, partiallycovers the two middle channels 24, 25. The lower cover element 32 closesthe lower channel 26 with the wire 30 contained therein and hasdownward-protruding bracing struts 34 disposed offset from one anotheron its circumference, which, when the interconnection element 10 isplaced against the end surface of the yoke ring 15, protrude between thewound stator teeth 16 and rest radially against the inner wall of theyoke ring 15 with frictional, nonpositive engagement. Both of the coverelements 31, 32 are fastened to the support 20, which can be carriedout, for example, by means of clips, gluing, or ultrasonic welding.

A terminal strip 36 injection-molded out of plastic is placed againstthe support 20 and is equipped with three connecting terminals 37, 38,39, each for one of the winding phases. The wire ends of the wires 27through 29 are connected electrically and mechanically to the connectingterminals 37 through 39 by means of hot-stacking. In the course of thewires 27 through 30, bent segments 35 are provided, which serve toconnect the wires 27 through 30 to the connecting pins 17 of the stator13. In accordance with the three-phase wiring 11 in which each windingphase has three parallel coils 12, the wires 27 through 29 each havethree bent segments 35 and the wire 30 has a total of nine bent segments35 in order to produce a star point comprised of the winding phases. Thebent segments 35 in the wires 28 and 29 that are contained in the twomiddle channels 24, 25 are routed radially over the channel rims of thechannels 24, 25 to the connecting pins 17 and the bent segments 35 inthe wires 27 and 30, which are contained in the upper channel 23 and thelower channel 26, are routed out the side through the channel openings231 and 261 and are then bent axially in order to reach the plane of theconnecting pins 17. The electrical connection between the bent segments35 and the connecting pins 17 is produced by means of welding,soldering, or insulation displacement. In an alternative embodimentform, the connecting pins 17 can be eliminated and the coil ends 121,122 can be welded directly to the bent segments 35.

The support 20 of the interconnection element 10 can have otherattachment possibilities for add-on pieces. The bracing struts 34simultaneously serve to center the interconnection element 10 inrelation to the stator 13. In addition, fixing elements can be providedthat automatically produce a correct association of the bent segments 35with the coil ends 121, 122 of the coil 12 when the interconnectionelement 10 is placed against the stator 13.

Naturally the above-described interconnection element is not limitedsolely to the interconnection of a three-phase winding with nine coils.With a corresponding adaptation of the number of bent wires and of thebent segments in the wires for connection to the coils, it is possibleto interconnect any winding with any number of phases and coils.

1. An interconnection element for a multi-phase winding (11) that is comprised of coils (12) and belongs to an electric machine, in particular a brushless mini motor, having a support (20) made of insulating material and conducting strips that are disposed on the support (20) and are for producing interconnections among the coils (12) wherein the electrical conducting strips are embodied in the form of bent wires (27-30).
 2. The interconnection element as recited in claim 1, wherein the wires (27-30) are contained in concentric channels (23-26), which are embodied in the support (20) and are offset from one another, partly in the radial direction, partly in the axial direction.
 3. The interconnection element as recited in claim 2, wherein the wires (27-30) are fixed in the channels (23-26) by means of two annular cover elements (31, 32) made of insulating material, which are placed against the top and bottom of the support (20) and affixed to it.
 4. The interconnection element as recited in claim 3, wherein the cover element (32) that is placed against the underside of the support (20) is provided with fastening means for spatially fixing it in the machine.
 5. The interconnection element as recited in claim 3, wherein an upper channel (25) is covered by the upper cover element (31), a lower channel (26) is covered by the lower cover element (32), and the upper cover element (31) has closing bodies (33), which are offset from one another in the circumference direction, protrude axially downward, and rest on two radially offset middle channels (24, 25).
 6. The interconnection element as recited in claim 1, wherein in the course of the wires (27-30), bent segments (35) are provided, which are for connecting the coil ends (121, 122) of the coils (12) of the winding (11).
 7. The interconnection element as recited in claim 6, wherein the bent segments (35) are routed out of the channels (23-26), partly by being routed over the channel rims and partly by being routed radially out lateral channel openings (231, 261).
 8. The interconnection element as recited in claim 1, wherein the support (20) is provided with a terminal strip (36) that has connecting terminals (37-39); one wire end of each of the wires (27-29) is attached to a connecting terminal (37-39).
 9. The interconnection element as recited in claim 2, wherein the support (20) is embodied in the form of a circular plastic ring into which the channels (23-26) are integrally formed.
 10. A stator for an electric machine, in particular for a brushless mini motor, having a stator body (14) and a multi-phase winding (11) that is comprised of coils (12) and is contained in this stator body, characterized by means of an interconnection element (10) as recited in one of claims 1 through 9 that connects the coils (12).
 11. The stator as recited in claim 10, wherein the interconnection element (10) is placed against one end surface of the stator body (14) and the fastening means provided on the support (20) are comprised of bracing struts (34) that are disposed offset from one another around the circumference of the support (20) and rest radially against the inner wall of the stator body (14) with a frictional, nonpositive engagement.
 12. The stator as recited in claim 10, wherein the coil ends (121, 122) of the coils (12) are placed against connecting pins (17), which protrude axially from the end surface of the stator body (14), and the connecting pins (17) are attached to the bent segments (35) in the wires (27-30) of the interconnection element (10) in an electrically conductive manner, preferably by being welded or soldered to them.
 13. The stator as recited in claim 1, wherein the coils (12) are embodied in the form of annular coils that are wound onto stator teeth (16), which protrude radially from a yoke ring (15) of the stator body (14). 